This invention relates to fluid displacement apparatus, and more particularly, to a scroll type fluid compressor.
Scroll type fluid displacement apparatus are well known in the prior art. For example, U.S. Pat. No. 801,182 (Creux) discloses a scroll type fluid displacement apparatus including two scroll members each having a circular end plate and a spiroidal or involute spiral element. These scroll members are maintained angularly and radially offset so that the spiral elements interfit to make a plurality of line contacts between their spiral curved surfaces, thereby to seal off and define at least one pair of fluid pockets. The relative orbital motion of the two scroll members shifts the line contacts along the spiral curved surfaces and, therefore, the fluid pockets change in volume. The volume of the fluid pockets increases or decreases dependent on the direction of the orbital motion. Therefore, scroll type fluid displacement apparatus are applicable to compress, expand or pump fluids.
Scroll type fluid displacement apparatus are particularly well-suited for use as a refrigerant compressor in an automobile air conditioner. Generally, it is desirable that the refrigerant compressor for an automobile air conditioner be compact in size and light in weight, since the compressor is placed in the engine compartment of an automobile. However, the refrigerant compressor is generally coupled to an electromagnetic clutch for transmitting the output of an engine to the drive shaft of the compressor. The weight of the electromagnetic clutch therefore increases the total weight of a compressor unit.
In a conventional scroll-type compressor, the orbiting scroll is supported as a cantilever from its driving mechanism, which is fixed to the rear side of the orbiting scroll. Furthermore, the fluid inlet port, which is formed in the housing, is placed adjacent the peripheral portion of the spiral element of the fixed scroll to introduce fluid into the interior of the housing without a pressure loss.
However, in the above-described conventional construction of a scroll-type compressor, lubrication or cooling of the bearing portions of the supporting construction or driving mechanism for the oribiting scroll may not be sufficient. Damage to the bearing portions may result.
One solution to this problem is shown in FIG. 1 and is described generally in pending U.S. application Ser. No. 521,256, filed Aug. 8, 1983. In this construction, a fluid inlet port 2 is formed in housing 1 and located at an outer peripheral portion of a spiral element 3a of orbiting scroll 3. A step portion 2a is formed in fluid inlet port 2. Step portion 2a projects radially inwardly from an inner wall of fluid inlet port 2. Housing 1 is formed with a first oil passageway 4, one end of which opens at the inner wall of fluid inlet port 2. A second oil passageway 5 extends from passageway 4 to a shaft seal cavity 6, in which is positioned a shaft seal assembly 7. In operation, refrigerant gas is introduced into the interior of the housing 1 through inlet port 2. The oil mist suction gas strikes against step portion 2a. The oil included in the suction gas is separated therefrom and accumulates on step portion 2a. Following the flow of suction gas, the accumulated oil flows into first oil passageway 4, and then flows out to the shaft seal cavity 6 through second oil passageway 5. The oil which flows into the shaft seal cavity lubricates and cools the shaft seal assembly 7 and returns to the interior of housing 1 while lubricating the other bearing portions.
In this mechanism, step portion 2a for separating and accumulating the oil must be formed in the fluid inlet port 2. Also, the oil connected between shaft seal cavity 6 and fluid inlet port 2 must be formed in the compressor housing, requiring increased wall thickness of the housing, and thus a more complex, larger, and heavier housing construction.